This research topic concerns the relation between metabolic rate and ROS production which is regulated by anti-oxidant systems. This relation and its changes are studied in the context of the animal adaptation to environmental factors (temperature, pressure, exercise) and are related to the capacity to maintain or to develop a performance.
These mechanisms are studied in vitro and in vivo respectively at the cellular (mitochondria and muscular permeabilized fibres) and tissular levels (muscle, liver). Some approaches are developed in our lab:
Cell volume regulation (fish, rat)
In that context, our objective is to characterize these three steps in fish cells which represent suited model systems for these studies and to determine interactions between environmental changes and cell volume regulation ability.
During its migration for reproduction the European eel (Anguilla anguilla) must cope with several extreme conditions: temperature (medium in the rivers, low in the oceans), salinity (from fresh water to sea water), fasting ( the eel eats in the river but not during migration) and finally pressure (migration is performed at depth). The energy requirement due to the migration is very high (swimming activity, gonads development and gametogenesis) which let few possibilities for extra physiological activities because the energy budget is restrained to the fish fat stores. Under such environmental conditions whose the effects can interact, is there a hierarchy in the physiological functions? Are these functions optimised? Is the fish able to cope with a new stressing conditions?
For both sexes, the interactions of different factors such as pressure, temperature, swimming, salinity are studied in terms of energy metabolism.
Sepsis remains the first cause of mortality in intensive care units despite the large amount of research conducted over the last twenty years. Sepsis is a pathological state associated with a systemic inflammatory reaction resulting from an infection. The difficulty in grasping sepsis lies in the fact that it is multifactorial and involves several interacting physiological mechanisms : inflammatory, cardiovascular, endothelial, haemostatic, mitochondrial energetic metabolism ...
Sepsis is associated with a dysfunction of the vascular endothelium associated with oxidative stress, hypercoagulation and hypoperfusion. In many cases, it results in organs failure (severe sepsis) and, ultimately, in a stage of septic shock.
One of our objectives is to investigate the role of the vascular endothelium in the evolution of sepsis from a localized inflammation to a fully developed septic shock. To reach that goal, we validate a standardized procedure using an instrumented rat akin to human patient clinical take care. This rat experimental model allows blood sampling (for acid-base analyses and serum biomarkers assays) and measures of cardiovascular activity (heart rate , blood pressure, blood flow), ventilatory rate and oxygen blood saturation level. Moreover, rings of the thoracic aorta are dissected for motricity tests to evaluate endothelial dysfunction. In the long run, we hope to able to reveal specific markers of sepsis and therefore improve current diagnostic abilities.
Moreover, we have shown that body temperature plays a key role in the evolution of sepsis. The current work aims at improving therapeutic care through the use of body temperature control.
Within the next few years, we intend to apply our standardized experimental model to drug testing and more particularly to specify their mode of action.
About 10% of worldwide deaths are due to traumas and 30 to 40% of those are linked to hemorrhage. During a state of hemorrhagic shock, a persistent systemic tissue hypoxia due to hypovolemia and loss of red blood cells is observed. To compensate for the lack of oxygen at tissue level, the anaerobic metabolism is activated. A lactic acidosis, the production of ROS and protons are observed thereby inducing inflammation and cell death the consequence of which can provoke patient death. Enhancing tissue oxygenation in case of hemorrhagic shock is paramount when treating patients. Hence, with Pr Y. Ozier and within the development of the trauma center (O. Grimault), our objective is to improve knowledge of the physiopathological mechanisms involved in the evolution of the hemorrhagic shock and therefore to acquire new means of diagnostic, thereby improving patient care.
ORPHY Laboratory has developed murine models of hemorrhagic shock and trauma. They allow to study the consequences of these shocks on tissue metabolism and vascular function as well as to analyse the kinetic implementation of the shock. Taking that into account, different treatment modalities are tested with a specific focus on blood substitutes. We therefore explore the efficiency of Hemoxycarrier HM-101 (extracellular haemoglobin of Arenicola marina developed by Hemarina Society) during the treatment of hemorrhagic shock.
UFR Sciences et Techniques, Université de Bretagne Occidentale
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Directrice : C.MOISAN (+332.98.01.62.63)
Directrice adjointe: M-A.GIROUX-METGES(+332.98.01.80.67)